Environmentally Safe Material to Store Hydrogen

The storage of hydrogen for use in fuel cell driven vehicles has been difficult due to the low density of hydrogen at standard temperature and pressure. Compressed hydrogen tanks are one method to store hydrogen on vehicles, but safety and weight percentage (wt%) of hydrogen relative to the storage device can be of concern. Although metal hydrides and nanoporous materials have been suggested to store hydrogen, gas hydrates offer an environmentally safe material to store hydrogen. The pressures required to have the same density of hydrogen as compressed gas are less and novel techniques that extract hydrogen from water might add to the hydrogen density.

Research in this project involves the use of hydrates to store molecular hydrogen in an inert state for automobiles, unmanned planes, and space travel. Although H2 can form hydrates in pure form, the pressures required for stability are enormous (>200 MPa). Binary hydrates with compounds such as tetrahydrofuran (THF) reduce the pressure issue but are limited in the wt% of storage. Moreover, THF is volatile and would contaminate the desired pure hydrogen gas phase. For this work, sH hydrates and semi-clathrate hydrates (Chapoy et al. JACS. 2007, 129, 746) will be studied to determine the feasibility of hydrates for H2 storage. Low temperature hydrates (below 150K) will also be studied for space exploration applications, where both hydrogen and water can be used.